Power shovel



1929. H. L.. MITCHELL ET AL Dec. l0,

POWER SHOVEL Filed April 16. 1926 2 Sheets-Sheet A TTORNEY` H. 1MITCHELL ET A1. 1,739,175

POWER sHovEL Dec. l0, 1929.

2 Sheets-Sheet 2 Filed April 16. 1926 @ma I l TTORNEYJ` Patente-d Dec.10, 1929` HOLGER L. ANI) ROLE` LJ'UNGKULL, OF MILWAUKEE, WISCONSIN,ASSIGN- -ORS T0 EVARNISCHFEGR CORPORATION,

RATION OF WISCONSIN Application filed April 16,

This invention relates to improvements in power shovels, and moreparticularly to those of the internal combustion engine operated typewherein the shipper shaft is chain driven from what is termed thedigging shaft77 mounted near the forward end of the revolvin platform orturntable of the machine.

iiiiculty has been encountered in raising and lowering the boom on thesemachines, due to the fact that it interferes with the tene sion ofthedriving chain previously mentioned, the pivotal axisof the boom beingbelow and in advance of the axis of the digging shaft so that thedistance between/'the v latter and the shipper shaft varies withadjustment of the boom. r

One object of the invention, therefore, is -to provide compensatingmeans in conjunction with the boom and chain for automaticallyregulating the tension of the'latter throughout various adjustments ofthe boom.

Another object resideslin the provision of improved brace rods for theboom including the provision of means for absorbing the shocks incidentto the side swipes or thrusts encountered by the dipper stick. d

. Other objects and advantages will. become apparent from the followingdescription taken in connection with the accompanying drawings whereinone form of the invention is illustrated.

Figure 1 is a slide elevational view of the front and of a power shovel,showing the improved tension means applied thereto; v

Fig. 2 is an enlarged plan View of Fig. 1, some of the parts beingremoved;

Fig. `3 is a side elevation of Fig. 2;

Fig. 4 is an enlarged section on` line 4 4 of Fig. 1;

Fig. 5 is an enlarged section on line 5-5 of Fig. 3;

Fig. 6 is a section on line 6-6 of Fig. 5; and

Fig. 7 is a bottom plan vieW'of one of the parts in Fig. 5. n

Referring more particularly to the drawings and first to Figs. 1, 2 and3 thereof, a clipper stick 1 provided at its outer Vend with av shovel 2of any suitable construction 1s mounted upon a boom 3, the latter beingpivotally attached to the forward end of the re-f OF MILWAUKEE,WISCONSIN, A CORPO- POW'ER. SHIOVEILV 1926. Serial No. 102,397.

volving platform or turntable 22. The socalled crowding vaction or backand forth movement is imparted to the dipper stick by mechanism ofwell-known construction which comprises,V in general, the sprocket wheel5 mounted on the digging shaft 4, the sprocket wheel 6 fixed upon theshipper shaft 7 and connected to sprocket wheel 5 by means of a sprocketchain 8, and suitable pinions (not shown) which are fixed on shippershaft 7 and engage racks 9 on the gnderside of the dipper stick.

As previously explained and from the arrangement of parts justdescribed, it will be apparent that uponpivotal adjustment of the boom 3the distance between the shipper shaft and the digging shaft will bevaried. Thus, it will be apparentthat the drive or sprocket chain ifpassed directly between sprocket wheels 5 and 6 would be extremely tautwhen the boom was in its lowermost position of adjustment, while anyadjustment from such point upwardly would result in slackin the chain.To provide against this diiculty the present invention, as above pointedout, contemplates the provision of means vfor automatically regulatingor controlling the tension of the cha-in upon adjustment of the boom,this means being so constructed and arranged as to maintain the chaintension at substantially a constant value. To this end, the inventioncontemplates, in the form thereof illustrated in the drawings, theprovision of triangularlyshaped members 10 and 11 arranged on eitherside of boom 3 and pivotally connectedthereto by means of a pin 12extending through the -f boom and the forward ends of these members.

A sprocket wheel 13\is arranged betweenmembers 10 and 11 and is held inoperative or assembled relation with lrespect thereto b means of apin'14 passingloosely throng this sprocket wheel and having its ends`mounted in members 10 and 11 and held base 19 and upwardly extendingspaced arms 2() and 21, is secured to the revolvable frame or platform22'of the machine by means of bolts 23, arms 2O and 21 embracing members10 and 11 and being connected thereto .by means of bolts 24 and 25 orthe like provided `with heads 26 and 27 arranged for sliding movement inslots'or grooves 28 formed in members 10 and 11.

The operation of the improved tensioning or equalizing device is asfollows: Upon elevation of boom 3, for example, through an angle ofabout 30 .degrees from the full-line p0- sition `thereof shown in Fig.3, the heads 26 and 27 vof bolts 24 and 25, respectively, will coactwith the grooves 28 in me bers 10 and 11 to cause pivotal movement ofthe latter in a counter-clockwise direction with respect t the boomabout pin 12 'as a center, vso that sprocket wheels 13 and 16 and chain8 trained thereabout assume the dotted line position shown, the contourand position of the slots or grooves 28 bein such as to cause just theright amount of plvotal movement of meinbers 10 and 11 with respect-'tothe boom to take up on the chain an amount equal to the play orlooseness which would otherwise result upon this elevation or adjustment of the boom due to the fact that the arcuate path of shippershaft 7 about the pivot pin 3a connecting the lower end of the boom toframe 22 is eccentric to and below the axis of rotation of diggingshaft- 4.' The contour and position of the grooves or slots 28 is suchthat upon lowering of the boom bolt heads 264 and y27,

which are relatively fixed, act to cause pivotal movement ofmembers 1()and 11 in a clockwise direction with respect to boom 3 about pin 12 as acenter, whereby more of the crowdling chain is made available tocompensate for the increase in the distance between the respective anddigging shaft 4.

For the purpose of providing for wear Ain chain 8, members and 11 maybeprovided proved means have beenl provided to autoi matically takeupfon the crowding chain 8 upon raising of the boom insuch manner thatthe tensionin the chain is substantially constant, the improvedtensioning or equalizing means acting in the reverse manner upon'lowering of the boom.

The boom 3 is provided at each side thereof with brace rods 32 connectedto the boom at their up er ends by means of a bolt 33 and threade attheir lowerJends to receive nuts 34, rods 32 being provided with theusual axes of rotation `of shipper shaft 7 turnbuckles, as shown. Ahollo'w cylindriaal member 35 is fitted over the lower end of each rodand provided with spaced apertured lugs 36 which receive a bolt 37whereby member 35 is pivotally connected to the front end of frame 22,bolt 37 passing through a suitable lug 38 withwhich the frame may beprovided.` A spring 39 is arranged upon each rod 32 and is compressedbetween nut 34 and a cap 40 loosely fitting the rod and closing the openend of member 35. The cap 40 is provided with inwardly extending,diametrically arranged fianges 41 spaced laterally from the cap body andadapted to lit between similarly .outwardly extending ianges 42 withwhich member 35 is provided at its open end.v

the arrangement being such that when cap 40 v is fitted upon member 35and given a quarter turn, the cap will be locked in posit-ion, as moreclearly shown in Fig.- 5. y Member 35 and cap 40 may be provided withapertured lugs 43 and 44, respectively, the lugs beine' arranged toregister when the cap is in locking position and'receiving a bolt 45 forholding the cap in this position. By means of the construction justdescribed, springs 39 provide a cushion to relieve the boom, dipperstick, the shipper shaft and the various other parts/from the suddenshock which would otherwise occur due to side swiping with the dipper,or laccidental engagement with an obstruction, lthe springs being ofequal tension vand acting normally to hold the'boomin alignment'with thelongit-udinal center line of the revolving platform.

The brace rods 32 and the cushion means orl springs 39 associatedtherewith have been shown applied to the boom of a power shovel, but ofcourse they may be used with equal effect for bracing the booms or likemembers of hoisting mechanism of other types.

While a definite embodiment of the inven-j tion has been shown anddescribed, it will be understood, of course, that various changes may bemade in the size, shape and arrangement f the parts without departingfrom the spirit of the invention or the scope of the claims. v

The invention claimed is:

1. In a machineof the characterl described, the combination with asupporting frame, a driving shaft rotatably mounted on said frame, aboom connected to said frame for pivot-al movement about an axiseccentric to the axis of rotation of said shafta shaft carried by saidboom, and a flexible driving element connectin said-shafts and travelingin a plane at rig t angles `to the axes of the` shafts, of meansassociated .with said element and in its plane of travel andcoactingrtherewith for automatically compensatii'igl for changes in therelative positions of' said shafts upon said movement -of the boomwhereby the tension in said element is maintained substantially constantthrough the en# ico..

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izov I tire range of movement of the boom with -respect to the frame. 'y

2. In a machine of the character described, the combination with asupporting frame, a

driving shaft rotatably mounted on said frame, a boom connected to saidframe for pivotal movement about an axis eccentric to the axis ofrotation of said shaft, a shaft carried by said boom, and a flexibledriving element connecting said shafts, of means associated withsaidelement and coacting therewith to compensate for changes in the relativepositions of said shafts upon said move ment of the boom whereby thetension 1ny said element is maintained substantially constant throughoutthe range of operation of the boom, said means includin a memberpivotally connected to said boon and a second member relatively fixedwit respect to said frame` one of said members being pro- A vided with'agroove, the'other of said members being adapted and arranged `totraverse said groove whereby said first' member. is

caused to change its angular relation with re-v engaging said element, amember supporting said means for pivotal movement about an axisrelatively fixed with respect to sai d boom, and a second member fixedrelatively with respect to said frame and coacting with said first-namedmember to cause said movement of said means upon pivotal movement ofsaid boom whereby said means acts tomaintain the tension of said elementsubstantially constant throughout the range of movement of the boom.

4. Ina machine of the character described, the combination with asupporting frame, a driving shaft rotatably mounted onsaid frame, a boomconnected to said frame for pivotal movement about an axis eccentric tothe axis of rotation 'of said shaft, a shaft carried by said boom, andan endless drive chain connecting said shafts, ofa pair of membersarranged on opposite sides of said boom and connected to the latter forpivotal `movement with respect thereto about an axis relatively fixedwith respect to the same, said members being provided with grooves, apair of sprocket wheels arranged between said members and rotatablysupported thereby, said wheels engaging the respective runs of saidchain, and elements fixed relatively *ith re- Y spect to said frame andadapted and arranged to traverse said grooves whereby said members arecaused to change their angular rela.-

tion with respect to said boom in such wise as to cause said sprocketwheels tro maintain the tension of said chain substantially constant forall positions ofthe boom throughout the range of movement thereof.

5. In a power shovel, the combination with a supporting frame, a boompivotally connected to said frame, a shaft carried by said boom, adriving shaft rotatably mounted on said frame, and an endless chainconnecting said shafts, chain take-up means comprising a memberpivotally connected to said boom, and a second member fixed relativelywith respect to said frame and engaging said first member to causepivotal movement thereof with vrespect to said boom upon angularadjustment of thelatter with respect to said frame. said first memberengaging said chain.

6. The combination with the boom and crowding chain of a power shovel,of means associatedtherewith for automatically regulating the tension ofsaid chain upon adjustment of the boom, said means including a memberpivoted to the boom and engaging said chain, and means for guiding saidmember in its movement incident to adjustment of the boom. i f

7. The combination with .the boom and crowding chain of a power shovel,of means associated therewith for automatically regulating/the tensionof said chain upon adjustment f the boom, said `means including avmember pivoted to the boom and engaging Said chain, and means forsupporting and guiding the free end of said member to confine andcontrol the movements thereof occasioned by adjustment of the boom. Y

8. The combination with the boom and crowding chain of a power shovel,of means associated therewith for automatically regulating the tensionof said chain upon adjustment of the boom, said means including a memberpivoted to the boom and engaging said chain. j

9. lhe combination with the boom and crowding` chain, of a power shovel,of means associated therewith for automatically reguf lating the tensionof said chain upon adjustment of the boom, said means including a memberpivoted to the boom andengaging downwardly upon both runs of said chain.

l0. rlhe combination with the boom and crowding chain of a power shovel,of means associated therewith for automatically regulating the tensionof said chain upon adjustment of the boom, said means including armspivoted to opposite sides of said boom and extending rearwardlytherefrom on both sides of said chain, a plurality of pins extendingbetween said arms, and sprocket wheels mounted on said pins and engagingboth runs of said chain.

11. The combination with the boom and crowding chain of a power shovel,of means associated therewith for automatically regujlating the tensionof said chain upon adjustment of the boom, saidmeans including armspivoted to opposite sides of said boom, a plurality of pins extendingbetween said arms, sprocket .wheels mounted on said pins and engagingboth runs of said chain, and means engaging one of said arms forcontrolling the movements of said sprocket wheels upon adjustment of theboom.

12. The combination with the boom and crowding chain of a power shovel,of means associated therewith for automatically regudescribed, thecombination of a supporting frame, a boom pivotally mounted on/theframe, a driving element on the frame, a driven element on vthe boom,the arrangement being such that the distance between the elements isvaried by pivotal movement of the boom, a fiexible connector associatedwith the driving element and the driven element, an equalizing deviceadapted for movement with respect to the boom and the framefor varyingthe path of travel of the flexible connector and means for positivelyactuating said equalizing device to com# pensate for the varyingdistance between the driving and driven elements upon pivotal movementof the boo-m so as to maintain the length of the path of travel of theflexible connector constant.

14. In an excavating machine of the class described, the combination ,ofa supporting frame, a boom, a pivot for securing one end ofthe boom tothe frame, a driving shaft and a sprocket wheel on the frame, a drivenshaft and sprocket wheel onthe boom, the arrangement being such that thedistance between shafts is varied by pivotal movement of the boom, asprocket chain connecting the sprocket wheel on the boom to the sprocketwheel on the frame, the path of travel of said chain being in a singleplane and means in said plane actuated by the boom for prethe path oftravel of said boom about its pivot` and means actuated by said boom forpreventing slack occurring in said flexible connector when the distancebetween the shafts is variedby movement of the boom about its pivot.

16. In an excavating machine of the class described having a frame and aboom pivoted thereto, two shafts adapted to rotate about parallel axes,one shaft beingimounted on the frame andthe other on the boom, aflexible connector for conveying torque from one shaft to the other andadapted to travel in such a way that it remains in a given plane, thearrangement being such that the distance between the axes of the shaftsis varied by pivotal movement of the boom, equalizing means formaintaining the length of the path of travel of'a point on the connectorconstant and means for automatically and positively actuating. said,equalizing means to compensate for the variations in the distancebetween the'axes of the shafts caused by pivotal movement of the boomover its entire range of movement.

17. In an excavating machine of the class described having a frame and aboom pivoted thereto,l two shafts adapted to rotate about parallel axes,one shaft bein mounted on the frame and the other on the oom, a sprocketchain for conveying torque from a sprocket wheel on one shaft to asprocket wheel on the other, the arrangement being suchthat the distancebetween the axes of the shafts is varied by pivotal movement of the boomand equalizing means for preventing slack in the chain when the boom ismoved about its pivy ot, said equalizing means consisting of a carrieractuated by the boom, means for constrainingthe movement of the carrierto a definitepredeterminedpathJJ and guides carried by the carrier forengaging both runs "of the chain.

` In witness whereof we hereto aiiix our sig natures.

HGLGER L. MITCHELL. ROLF LJUNGKULL.

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venting slack in the chain when the boom is rotated about its pivot.

15. In an excavatingmachine of the classl described, a frame, aboom'pivoted to the frame, a shaft on ,the boom, a shaft on the frame, acontinuous flexible connector associated with said shafts for conveyingtorque4 from vone to the other, the path of travel of' said iiexibleconnector being in the plane of

